Cardiovascular disease (CVD) accounts for nearly half the mortality, and extensive morbidity, among patients with renal failure. Co-morbid illness and traditional cardiac risk factors do not fully explain the epidemic proportion of CVD observed among dialysis patients. Secondary hyperparathyroidism (SHPTH) is a disorder of calcium metabolism found in renal failure that has been linked to cardiovascular (CV) pathology in experimental models of disease. Clinical evidence relating SHPTH with CV outcomes is limited.The three major aims of the proposed study are 1) to estimate the relationship between serum markers of SHPTH and clinical CV outcomes among patients with renal disease, 2) to estimate the relationship between medications regimens used to treat SHPTH and cardiovascular outcomes, and 3) to recruit a new cohort of dialysis patients to participate in pilot studies and serve as a foundation for future research into the relationship between SHPTH and clinical CVD. Two parallel activities will be conducted to address out scientific aims. First, we will study an established cohort of dialysis patients from the United States Renal Database System (USRDS) and an established cohort of chronic renal insufficiency (CRI) patients from the Veterans' Administrations' Consumer Health Information and Performance Sets (CHIPS) database. The serum markers of interest are intact PTH, calcium, and phosphate. Medication exposures of interest are dosages of phosphate binders and calcitriol. Second, we will recruit a new cohort of 100 dialysis patients from the Northwest Kidney Center and the Veterans' Administration Medical Center dialysis centers.We will ascertain traditional and novel serum markers of SHPTH among our patient cohorts, and then follow them for the development of subsequent CV related hospitalizations. The primary outcome is time to first cardiovascular hospitalization or cardiovascular death. The proposed study aims to shed light on the relationship between a common renal related metabolic disorder and the epidemic burden of CVD found among this patient population.